Flame Sister
by Kyoto-Himes Akio and Kyou75
Summary: Roy Mustang's past is somewhat of a mystery. Actually everyone's past in the military is a mystery. But Roy's past unravels when his sister comes to town. A real flame alchemist with a curse. Just one touch from her and you burn. She can't escape it.
1. Chapter 1: Arrival

**Disclaimer: I do not own Fullmetal Alchemist. This is non profit. This is just for enjoyment. Only my OC belongs to me. All other characters related to this anime belong to their creator.**

**[Akio's Story]**

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Chapter 1:

Flame Sister

_The day she was born, was one of the worst days for the Mustang family. The day she was born, their house had gone up in flames. It wasn't the best way for a baby to be born, but it had decided her fate, her cursed fate. As she grew, so did her fire. Soon, not even her body could contain her heat. Everything she touched would incinerate at her touch. You see, the fire that had destroyed her home, was only able to be controlled and extinguished by being absorbed by her. That was her cursed fate. That. This, is my cursed fate.  
__**-Yei Mustang**_

Roy Mustang sat at his desk at the military base. He was known as the "Flame Alchemist" because he was able to control fire through alchemy. Every time he thought about being called the "Flame Alchemist" he knew the title belonged, very well, to his younger sister. He began to wonder what his younger sister was up to at that moment. He hadn't seen her since she was 7, which was about 10 years ago. _I bet she's all grown up now._ Roy thought to himself.

"Hey Mustang, you got mail." Jean Havoc yelled as he walked into the room with a pile of mail in his hands. Roy didn't bother to get up, he just extended his arm across his desk and opened his hand expecting to receive the letter. Jean just starred at him, "You expect me to bring it t you?" Roy nodded without looking at him. Jean didn't move a muscle, he had no intention of walking over to Roy then walking back across the room to his own desk.

A small black figure ran from Riza's desk side to Jean and started jumping up and down barking at him. It was Black Hayate, Riza's dog. Jean looked down smiled, and handed the dog Roy's letter. Hayate happily took the letter in his mouth and walked over to Roy's side and dropped the letter on the ground. Roy didn't bother to look at the return address, instead he just ripped open the letter and began to read it out loud.

"_Dear brother,  
__I hope you are doing well. Mother and father are doing quiet fine. And so are our other siblings.  
__I am about to turn 17 and I thought of visiting you as my birthday present.  
__Mother and father don't mind, but wanted me to let you know ahead of time.  
__I don't know your exact location, but I'm taking it you're still at this address.  
If not then I'll find out for myself, since I am leaving home at this moment.  
__There are some things I would like to discuss with you in person anyways.  
__I hope to see you soon big brother.  
__-Little Flame Alchem.  
__-8/15"_

Roy starred at the letter, "August 15th?" he said to himself. He moved a couple of piles of papers around his desk until he found his calendar. Today was August 15th. "She couldn't have traveled here so quickly, it took me at least 10 days to get here from home." Everyone else in the room had heard the letter and were starring at Roy with disbelief. They had not known that he had a sister, or any siblings at all.  
Roy grabbed the phone on his desk and began to dial his family's number. "Hello?" It was an older women's voice.  
"Mom?"

"Roy is that you?"

"Yes mom, I need to ask you a question about Yei."

"Oh is she there already? She travels fast doesn't she?"

"No she isn't here yet mother. I need to know when she did leave home though."

"She left about 4 days ago." Right when his mother said that, one of the military officers came into the room with a girl who looked identical to Roy, just a little shorter, and long flowing black hair, with a mix of red, orange, and yellow highlights to represent fire. Roy starred at her for a moment, forgetting about their mother on the other line. "Roy! Roy! What's the matter son?!" It was their father on the phone now.

"Nothing father, just tell mom, Yei is here now." And with that said, he hung up the phone and motioned for the officer to go away. The officer did as told, but Yei stayed where she was. Eyes on moving. Body still.

"Young lady is there something you need?" Jean asked her from his desk, since his was closest to the door. Yei shook her head, her eyes locked onto Roy.

For awhile there was only silence. Everyone in the room starred at the unmoving Yei for a good couple of minutes. "Yei, you've grown." Roy said, breaking the silence, not being able to stand it for very long.

When they were younger there was no silence in any room if both Yei and Roy were together. They were either arguing or laughing no matter what. The silence Yei created when she came to the base was unnatural to Roy. He couldn't understand why there was silence with Yei. Why she had become silent at all. Was it because he had left home about 10 years ago? Or had something happened to Yei while he was gone? _She said she needed to ask me something in person, in her letter. So why is she giving me the silent treatment for?_ Roy asked himself.

"Flame. Alchemist." Yei whispered.

"What?" Everyone in the room replied. Yei still didn't remove her eyes from Roy.

"Flame Alchemist. That's what you're known as around here isn't it Roy?"

"Yes it is, thought now that you're here. I don't believe I deserve that title."

"But I can't do alchemy like you can."

"No one else can create flame alchemy like Roy can." Riza replied for her desk.

"No one else can?" Yei said taking a step into the room.

"Nope Roy is the one and only." Jean said with a smile and satisfied look on his face.

"Really? Is that true Roy?" Yei asked him. Roy didn't move. He knew that when Yei's voice was neutral something was wrong. "If it's true Roy, then you won't mind seeing me outside this building now will you?"

"Why do I have to meet you outside the building for Yei?" Roy asked his voice shaking a little, but not noticeable to everyone except Yei.

"I want to know if what you're friends are saying is true, that's all." Yei said, then disappeared out of the room, quicker than a blink of an eye.

"She really is quick." Roy said to himself as he stepped around his desk and walked outside the room. Everyone in the room followed him, they wanted answers.

Once Roy was outside standing about 20 feet away from his sister, a small crowd began to form around them. "Why did you call me out, Yei?" Roy yelled.

"I thought I answered that inside?" Yei said with a small smirk. She could feel her brother's fear. She could hear it in his voice. She grew up with him, even if they had been separated for a good 10 years, she could still tell when he wanted to beg for mercy. Even when nothing had happened yet. "I want to see how good your flame alchemy is brother!" She yelled back at him.

Roy held out his hand, ready to snap his fingers and create a fire. Yei carefully examined his hand from where she stood. She saw a seal on his white gloves. _So that's how you make your flames, brother. You use a seal._ She thought to herself. Yei pointed to a tree near Roy. "Burn that tree." Roy did as he was told. It stayed on fire, a few people around it moved to go get water, but Roy told them to leave it alone. The tree finally was put out of it's misery 10 or 20 minutes later.

Yei yawned. "That took forever to go out." She yelled from where she stood.

"How fast can you make fire destroy a plant?" Someone yelled from the crowd.

"How fast? In about 30 seconds."

"That's impossible!" Someone else yelled from the crowd.

"It's very much possible." Roy whispered to himself. Only Riza heard him.

"What do you mean that it's possible, Mustang?" He asked him.

"She can destroy a tree 10 times bigger than the one I did in 60 seconds or less."

"How is that possible?!"

"You'll see." Roy directed his attention back to his sister. "Yei! If these people don't believe you, then go destroy that tree over there." Roy pointed to a tree about 5 feet behind the crowd. It was exactly 10 times bigger than the one he destroyed.

Yei turned around and smiled. She would love seeing this tree go up in flames. She turned her head back towards her brother, the smile still on her face and said, "Whatever you say Roy." Then proceeded walking towards it.

"How's she going to burn down that tree in 30 seconds?" Someone whispered in the crowd.

"It isn't possible to burn it in 30 seconds. It's even impossible for Colonel Mustang." Another whispered.

While the crowd whispered these impossible thoughts, Yei stood before the tall tree and took off her black and red gloves that she wore. She held them in her mouth and then touched the tree. The tree began to turn to ash right where she touched it. In about 45 seconds, the tree was all in ash. The crowd starred at her in disbelief. Yei ignored their stares and walked over to Roy. She mumbled something.

"What?" he replied. Yei pointed at her gloves with her eyes. Roy took them out of her mouth.

"Soak those in water, and then put them back on for me, please." Roy gave her a confused look, but told her to follow him back to the office. She did as she was told. Everyone else from Roy's office followed them back as well. None of them could believe what Yei had just done, she had just out shined the Flame Alchemist, with… They had no clue what she had used. No one knew, except for the Mustang family.

Roy went to the bathroom with a bucket and filled it up with cold water. He took it back to his office and put it on the ground next to his sister, who was standing near the window with her hands balled up in fists. Roy threw her gloves into the bucket of cold water, then began to walk towards her, but then heard a sizzling sound. He looked over at the bucket and saw steam coming from it.

"The gloves collect your body heat?" Roy asked looking back at his sister.

"The gloves and boots collect the heat that comes from my hands and feet. It's a good thing the heat is only able to escape from those areas."

"So it's just getting worse as you grow older isn't it?"

"Yep it is. I need specially made boots and gloves just to live a normal life."

"So when did you get those gloves and boots anyways?'

"About 5 years ago."

"Anything else I need to know since I left home 10 years ago?"

"Big sis got married."

"To that guy she was dating?"

"No some other guy. I forgot his name though."

"And how about Tai? Is he getting any better?"

"Their trying to find a cure. Still trying actually."

"It's a miracle he's still living through."

"Yes it really is. Every misses you at home. They even had me bring you a few things too." Yei was about to grab her bag off her back, but slowly balled her hand back into a fist.

"What's the matter?" Roy asked, confused. He had totally forgotten that Yei needed her gloves.

"The things will burn. I think my gloves should be cooled down enough by now."

"Should I also cool down your boots?" Roy asked jokingly.

"No, the gloves are good for the day. The boots are for tonight." She said with a laugh. Roy handed Yei back her gloves. Yei just starred at them.

"Aren't you going to put them back on?"

"I can't. If I touch them, they'll burn." Roy gave her a confused look, but put them on anyways. He then took notice of everyone back in the office. He cleared his throat.

"Everyone this is my youngest sister Yei." He said patting her on the back. Everyone just starred at her. "She caused quite a commotion downstairs didn't she?"

"How were you able to burn that tree down so fast?" A guy with glasses asked her.

"It's a family secret, that Roy doesn't know." Yei said flatly. No one outside of the Mustang family knew of Yei's curse. No one outside the family was allowed to know. If anyone were to find out then they were to be burned alive. It wasn't something Yei was fond of doing. She didn't even like burning trees at first when she was little, but when she found that, burning trees was the only thing she was allowed to touch she got use to it.

"Was it necessary to cause a scene like that in the first place?" Riza asked her voice had a tint of annoyance in it.

"Yes it was. Parents orders, speaking of parents. I almost forgot." Yei reached behind her to open up her book bag that she carried with her. "Mom, dad, and our 3 siblings all sent something along with me to bring to you Roy." Yei dumped all of her contents onto his desk. There were several books about dating in there and a few house utensils.

"These are what they sent me?" Roy asked a little annoyed.

"Yep, you know how they are." Roy knew exactly how their parents were. They even loved sending him such things in the mail.

"So where are you staying tonight, Yei?" Roy asked her as he planned to burn all of the books later tonight like he usual did with his parents' gifts.  
"I was thinking maybe a hotel for tonight."

"Roy, why don't you let her stay at your place instead?" Jean asked.

"Not tonight."

"Why not?" Riza asked.

"I have to clean up. I didn't even expect her until today. You mind if she stays with you Riza?"

"I only have one bed and that's it."

"What about Huges?" Jean asked.

"I really don't mind staying at a hotel for a night." Yei interrupted.

"Nonsense. You'll just be wasting your money." Riza replied as she picked up the phone. "I'll give Huges a call. I'll bet he'll be delighted to take you in, especially if you're Roy's sister." There was no more arguing. Yei couldn't even come up with a better excuse on not wanting to intrude on these people she didn't even know.

About 4 minutes later Riza hung up the phone. "Huges said he'll be delighted to take her in for a night. She'll give the Elric brothers some company for tonight. He say's he'll stop by the office right before he heads home to pick her up."

"Perfect. Thank you Riza for setting that up." Roy said.

"Yes thank you." Yei replied with a bow towards Riza.

"No problem."

"I had better hide…" Roy suddenly said as he inched towards a closet.

"Why's that big brother?"

"Huges scares me until his daughter is born."

Everyone in the room began to laugh. Yei knew she would love being around here for awhile, but she had to remember there were some things she needed to do before she could think of any enjoyment. She didn't want to burden these people for more than just one night. She didn't even want to burden her brother, but he would be part of it, even if she tired avoid it.

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A/N: Hey there people Akio here. i know that me and kyou haven't updated our other story lately, but... yeah i think we're just going to hold off on that for a long while. School's come up and a lot of other stuff, so we're kinda busy lately. This story was just made out of lesiure and boredom on my part.


	2. Chapter 2: Elric Brothers Meet Yei

******Disclaimer: I do not own Fullmetal Alchemist. This is non profit. This is just for enjoyment. Only my OC belongs to me. All other characters related to this anime belong to their creator.**

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Chapter 2:

**Elric Brothers meet Yei**

_**Overview: Yei Mustang was born with a curse of fire. She's been separated from Roy for about 10 years. So she's come to visit him for her birthday and causes a scene in front of the whole Central Headquarters. Yei didn't have a place to stay for one night, but Riza helped with the arrangement.**_

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_One small flame was all it started out as. Just a small flame inside my body. That's all I thought it would stay as, I didn't think it would grow so much. I didn't think it would be such a hassle to have this curse. I didn't know she would die that day. And I didn't know I would have been the one to kill her. I hate this curse I hate it. This flame needs to die away, but if it dies away. So do I._

_-Yei Mustang_

Huges skipped around as he finished up his work for the day. He was so excited to meet Roy's younger sister. He couldn't even believe that Roy had kept this fact from everyone in the military. He had to wonder if she looked exactly like Roy or much different. He couldn't even hold in his excitement to meet her, considering he threw up the books he was carrying and said, "I can't wait to tell her about my soon to be born daughter!" Everyone in the room just starred at Huges and told him to finish up his job.

Huges finished up the last of his work and rushed over to Mustang's office. He threw open the door and yelled, "Roy! I never knew you had a sister!" Everyone in the room starred at him.

"Shut up, Huges. You better take care of my sister and nothing else." Roy threatened from his desk. Huges only smiled.

"Why would I want to hurt you're precious little sister?"

"You don't." Huges turned to a corner of the room to see Yei playing with Black Hayate. She didn't take her eyes off the dog and continued to play with him.

"You must be Roy's younger sister?" Huges asked a little confused, because she looked nothing like Roy. Her eyes were two different colors he saw. They looked a bit like the color of fire. Her hair was also different from Roy's it wasn't pitch black dark, it was a shade of different colors. Her face structure was much more perfect than Roy's, from what Huges could tell.

"Yes I am. You must be Huges," She said as she picked up Hayate and walked over towards Huges, extending her right arm, "Please to meet you. I'm Yei Mustang."

"It's nice to meet you as well, Yei." Huges said shaking her hand.

"Yei let me have a word with you for a second." Roy called from his desk. Yei gave Huges a half bow and walked over to Roy, with Hayate still in her arms.

"Remember not to lose you're temper tonight. You have what you need correct? To control it? And be nice as well. Huges's wife is expecting a child soon." Roy scolded her.

"Yeah, yeah I get it okay Roy? I'll be good. It's not like I'll loose my temper so easily anyways tonight. It'll take time for that to happen anyways." Roy gave her an unsatisfied look that Yei didn't take notice of. He wasn't certain to her promising words. He had been away from her for 10 years. For all he knew, her temper could have worsened or calmed.

Roy lowered his head so that his forehead was almost touching hers. Yei was about to take a step back, but found that couldn't, there was a box behind her. "You can't burn me Yei. Remember, the curse doesn't work on family." Yei lowered her eyes to the ground. She had forgotten that rule. "Be safe. I hear there might be a snow storm. Stay inside if it turns out there is one alright?" Yei nodded, knowing full well the consequences if she were to get stuck in such a storm.

About 20 minutes later Yei was in the car with Huges headed towards his place, or well that's what she thought until Huges stopped at a store. He told her to stay in the car while he did some shopping; she did as she was told. Huges was gone for about half an hour, when he returned to the car, Yei was playing with string that she had brought with her. Huges not only had an arm full of groceries, but also two teenage boys were with him. Well one looked like a teenage boy the other was in a suit of armor. Which she found quite unusual.

Huges opened the door and told the boy in the suit of armor to sit in the back with Yei and had the other boy sit up front. The boy in the front had long braided blonde hair, she had never seen any one with such long hairs as him. He also wore a red cape around him.

"These are the Elric brothers, Yei. I'm pretty sure you must have heard about them from Roy. Haven't you?" Huges asked as he began to drive off. Yei shook her head.

"Roy hasn't written home for about 3 years." Yei replied almost in a whisper.

"What's your relationship with Roy Mustang?" The boy in the suit of armor asked.

"I'm is younger sister. I'm 16 turning 17 in a couple days."

"I'm Alphonse and that's my brother, Edward." Yei smiled at him. She didn't feel like questioning why he was in a suit of armor at the moment. For all she knew. He could have a curse on him, just like she did.

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All three teenagers helped Huges with the groceries and brought them inside. They were all welcomed by his wife who you could very much see was about 8 months pregnant. Huges went off into the kitchen to make dinner, Yei offered to help, but he said otherwise. "You're our guests for the evening. Please make yourselves at home. I'll prepare dinner. The three of you just wash up." Yei found no use arguing and followed Edward, Alphonse, and Mrs. Huges up to the two guest bedrooms.

Yei got settled in her room and began to read a book. She heard the phone ring, but didn't pick up because it wasn't her phone to answer. After the second ring the line went dead. She heard Mrs. Huges in a distant talking to someone on the other line. She soon zoned out, entranced by her book. A knock at the door brought her out of her trance. She got up and opened the door to find Edward standing there, half a head shorter than her.

"Huges wanted me to get you for dinner since you wouldn't come down when he called." He said.

"Oh I guess I couldn't hear him. When I get into a book I usually don't hear anything else." She said as she stepped out of her room and closed the door.

"How old are you?" Ed asked as they walked down the stairs towards the dinning room.

"I'm going to turn 17 in about 5 days."

"Really? So you're the same age as me then."

"You're 16?"

"What age do I look like?" Ed asked with a hint of annoyance, towards her possible answer. _'If she says 10 I'm going to lose it on her.'_

"About 14 or 15," she answered calmly.

"I thought you would have said 10 or 11." Yei just smiled and shook her head as they walked into the dinning room and took their seats. During dinner Huges tried to get some embarrassing information on Roy, but Yei didn't have any since he had left 10 years ago.

"I could barley remember what he looked like, since he left." was her reply after Huges complained. Even if it was a lie. Roy's weakness was, her own. A curse no one outside of her family was to know.

Yei felt more energy at the dinner table tonight than she had any other night in her life. Her family wasn't really the energetic type. They more a bit more serious since the day she was born. Her siblings had always said, "Before you were born dinner was really the only time any of us had fun, but now. There is no fun at all in this family because of you." Usually her siblings only said that when they wanted her to feel bad, but that was only once in a blue moon when they said it. But even if it was only a few times. It still hurt Yei to hear it spoken. To hear that she had stolen, actually taken, her family's happiness away from them after just being born.

While Edward and Yei helped to clean the table, Mrs. Huges doubled over in pain. Mr. Huges went over to help her, but all she screamed was, "The baby's coming." Huges helped her to the couch then rushed to the phone, but there was no dial tone.

"Dammit the phone line's out." Huges cursed as he slammed the phone down. "You three stay here and take care of my wife while I got out on foot and get a doctor out here."

"What?!" All three of the teenagers yelled as Huges put on his coat and boots.

"I said stay here and take care of my wife." He said before he slammed the door closed.

Edwards, Alphonse, and Yei all starred at each other. None of them knew what to do with a woman in labor. They all stopped starring at each other once they heard Mrs. Huges yell in pain. "Someone get me water!" She yelled. Yei ran straight into the kitchen and got a cold glass of water she helped, Mrs. Huges up to drink it.

"Ed, go get me a bucket of cold water. Al, go get a towel from, I have no clue where they keep the towels." Yei ordered. Both of the Elric brothers did as they were told, but in a panicy way. Once they brought Yei what was she asked for Yei soaked the towel in the cold water and put it on Mrs. Huges head. After that, none of them had any clue of what to do for the next hour that Huges was gone. They were all thankful when he finally came back with a doctor and the baby girl was born.

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Yei lay on the bed in her room exhausted from tonight's event. She took out the small radio she brought with her and turned the volume up high enough to fill the room. She dumped her clothing on her bed and began to change. As she took her shirt off to she didn't hear the knock on the door.

Ed knocked on Yei's door to ask her something, but he got no answer. He pressed his ear to the door and heard music. _Maybe that's what she couldn't hear me_, he thought to himself as he slightly opened the door. "Sorry to intrude on you Yei but –" He stopped talking as he saw that Yei had her shirt off. He quickly turned around and shut the door.

Yei turned around, covering herself with her shirt, as she heard Edward's voice. She was thankful that he hadn't seen much and had left quickly. She didn't want to have to explain anything to him. She quickly got changed and left her room.

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"Did you ask her brother?" Al asked as Edward came back into the room.

"No she was changing when I came in. That was embarrassing."

"Oh, well it's too bad that she's only going to stay here one night then go stay at Mustang's place."

"Where'd you hear that?"

"Huges told me."

"Oh. Something's strange with her though."

"Why do you say that, brother?"

"When I accidently walked in on her. I caught a glance at her back."

"What about it?"  
"It looked like she had burn on it."

"I wonder is she got into an accident."

"That could be the possible reason." Ed said as he got into bed.

"You're not going to try and ask her again?" Al asked as he watched his brother climb into bed.

"Not tonight, it's just too awkward." He said as he flipped his back to Al and fell asleep. Al didn't say anything just nodded his head and fell silent himself.

Ed wasn't certain if his brother was asleep or not since he was in a suit of armor because of him. So Ed cautiously turned on the bed to stare at the ceiling. _I have to wonder what happened to her. Did Roy to something to her with his flame alchemy? Or did someone else burn her?_ He thought to himself. Al and himself were to leave Central soon and continue their journey in search of the Philosopher's stone. He knew he wouldn't be getting much information about her through anyone else. _I'll ask her tomorrow if she would like to take accompany us, she seems to be lonely._ Was Ed's last thought as he drifted to sleep.

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**A/N: I truthfully had no clue how to end this chapter, but that was the best I could do. I will probably revise it later if I can.**


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